Pressure device for hydraulic brakes



June 25, 1946, BE KLJ 2,295,8Q6

PRESSURE DEVICE FOR HYDRAULIC BRAKES Filed June 15, 193B Patented June25, 1940 PATENT OFFICE PRESSURE DEVICE FOR HYDRAULIC BRAKES Jii-iBlenkij, Olomouc, Czechoslovakia Application June 15, 1938, Serial No.213,938 In Czechoslovakia February 9, 1938 12 Claims. -5415)Thisinvention relates to a further improvement inthe pressure devicesfor the hydraulic brakes of motor vehicles, these devices beingconstructed in such a way that the master pressure cylinder is able tosupply fluid to the pressure conduit and the brake cylinders in thevehicle Wheels, both during the braking movement of the pedal or handlever and during the return movement, that is, the releasing movement ofthe pressure piston. By the arrangement according to the invention,there is obtained a greater reliability in the action of a valvedisposed between the fluid supply container and the master pressurecylinder, and accordingly theeosts of production are reduced and thearrangement as a Whole operates more perfectly. The invention primarilyconsists in the arrangement of an auxiliary piston, loaded in thedirection of suctionby a spring, and disposed between the working pistonof the device and the fluid supply container, and in the arrangement ofa suction valve located in this auxiliary piston. The arrangement issuch that the auxiliary piston at the end of its stroke, effectedagainst the action of its spring, opens the connection of the suctionspace or chamber of the pressure cylinder of the device to the supplycontainer. Furthe! characteristics of the invention will be seen fromthe following description of one example of construction as illustratedin the accompanying drawing, in which Fig. 1 shows diagrammatically alongitudinal section of the device according to the. invention, withparts in their operative position, and I Fig. 2 shows a part of thelongitudinal section with. parts in their position before filling withIn the form of construction shown, the apparatus is formed with a masterpressure cylinder I in which apiston 2 works, the piston rod 3 of whichpiston passes through a suitable packing 4 provided in the cylinder Iand terminates in a: connectingmember 5 on which acts a pedal or handlever, not shown, for actuating the hydraulic brake. The working pistonI is therefore constructed as a differential piston which hasuon itsworking side 6, that is, the side producing the braking effect, anannular surface, but on its other side a full working surface I.Adjacent the annular surface S of the piston is theworkin'g space orchamber 8 and adjacent the full surface 'I the suction and pressurespaceor chamber 9 of the cylinder I. loaded by a compression spring I I]which opposes the braking stroke thereof. On the full work- The piston 2is ing surface I there is provided a member II, which is screwed intothe piston, and contains a pressure ball valve I2 loaded by a spring I3.The travel of the valve I2 is limited by a stop I4.

In front of the full working surface "I of the piston 2 there isarranged a fixed transverse Wall I5 which is held in position by anoffset part It in the cylinder I and a resilient positioning ring I6" orby two resilient positioning rings. The transverse wall I5 is formedwith a fluid passage I'I, whilst on the face of the member II of thepiston 2 there is provided a radial groove 3%. Fluid passages I8 arearranged at the ball valve I2 and a longitudinal and transverse bore I9,which connects the passages I8 of the valve I2 with the workingspace 8of the cylinder is disposed within the piston 2. A stop 33 is mounted onthe wall IE to openthe valve I2 when the piston 2 is in its restposition, thus placing the chambers 8 and 9 in direct communication. A20 b -pass 33', as shown in Fig. 2, may be used to supplement or inplace of the stop 33, the bypass opening into chamber 8 immediately infront of the piston 2 when the latter is in its rest position. Anauxiliary piston 20, which is 25 provided on the side facing thetransverse wall I5 with a packing cup 2I, is arranged in the cylinder 1nfrontof the transverse wall I5. The piston 20 is pressed against thetransverse wall I5 by means of aspring 22. Asuction valve 26, whichbears on the cup 2| so that the latter forms at the same time theseating for the valve 24, is mounted in the auxiliary piston 20 by meansof its tubular open ending spindle 23 having beneath the valve 24 aconnecting aperture23'. 35 The valve 24 is pressed against the packingcup 2| by the pressure of a spring 25 interposed between a collar 26 onthe end of the spindle 23 and the transverse wall of the piston '23. Thespace 21 in the cylinder I behind the auxiliary piston 20, which isclosed by the base 34 of the cylinder I, is connected by a bore 29 inthe cylinder wall and a pipe 29 to the interior of the fluid supplycontainer 28.

In order to secure the master pressure cylinder Ito the vehicleframework, a flange 30 may, for example, be provided, by means, of whichthe master pressure cylinder can be secured to any suitable point, forexample to a flange of the vehicle frame. Instead of a flange any other50 means, for example two adjusting nuts, can be used for securing thecylinder I to the vehicle.

In the drawing, Fig. 2 shows the parts of the device in a positioncorresponding to the condition prior tothe filling of the entire devicewith fluid. After being filled with fluid and exhausted of air thedescribed device operates in the following manner:

On the first braking movement of the pedal or hand lever (starting fromthe position of the parts according to Fig. 2) the piston 2, by means ofthe member 5, is moved in the cylinder I to the left of the drawing. Inthis way the space 8 in the pressure cylinder i is diminished in sizeand the fluid is forced out of this space through the connecting branchpipe 3! into the pressure pipe 22 leading to the brake cylinders in thevehicle wheels, not shown in the drawing. At the same time the space tbehind the piston 2 increases in size and the fluid from the supplycontainer 28 opens the valve 24 and passes through the passage ll of thetransverse wall IE to fill the space a. On the return movement of thepiston (to the right of thedrawing) the valve 24 is closed by thepressure of its spring 25 and by the action of the excess pressure inthe space 9 and the fluid in the space t opens the ball valve H2 in thepiston 2 and flows past this valve through the passages i8 and the boresi9 into the space 8 of the cylinder i. return movement of the piston, nosuction effect, and, therefore, he reduced pressure can arise in thisspace a. At the end of the return move ment of the piston 2 the ballvalve 12 bears against a stop 33 arranged in the transverse wall l5 andis lifted by the same into'its open posi tion. If, on the returnmovement of the piston 2, the fluid pressure in the space 8 of thecylinder I has attained a value equal to the force of the spring 22loading the auxiliary piston 2%], then this auxiliary piston commences,together with the piston 2, to move against the pressure of the spring22 towards the rear end 3:3 of the cylinder l. The valve it isaccordingly also moved until,

nearly at the end of the stroke, the end -of its tubular spindle 23bears against the rear end 3% (see Figure l) and is thereupon liftedfrom its seat, so that the excess fluid escapes from the space 9 backinto the container 28. Directly after this the auxiliary piston 28 isagain pressed back a short distance towards the left (in the drawing) bythe spring 22 and in this way the suction'valve 24 is closed again byits spring 25, so that the auxiliary piston 26] remains in theneighbourhood of the rear end as of the cylinder I, that is, accordingto the drawing, the right-hand position, with the spring 22 compressedas illustrated in Fig. 1. The spring 22 exerts a continuous pressure onthe fluid, in the space 9 of the master cylinder 5 and in the space 35behind the transverse wall H5, in front of the auxiliary piston 2B, andrepresents a supply of pressure fluid which is always available to makeup for any loss of pressure fluid which may occur in the working space 8of the cylinder! and in the brake conduit 32, as the pressure of thesupply fluidin the spacesQ and 35 is transmitted through the open ballvalve i2 to the fluid in the space 8. As can be seen, the pressure inthe spaces or chambers 33, 9 and 35 of thecylindcr i cannot exceed acertain amount determined by the strength of the spring 22, which is sochosen as not to oppose the possibility of a removal of the load on thebrake blocks in the vehicle wheels by the action of the springs drawingthese blocks together.

With further braking movements of the pedal or the hand lever, theauxiliary piston 2!], on the movement of the working piston 2, movestowards the left, until it reaches the end of its stroke. This end is,for example, determined by anaxial For this reason, even on the flange3? of the stationary transverse wall [5, the valve 24 lying in thehollow space of the. annular flange 31. Should a further brakingmovement of the piston 2 then take place, the valve 24 opens and thepiston 2 draws in fresh fluid from the supply container 28. On thereturn movement of the piston 2 the above described operation takesplace.

In the arrangement according to the invention, it is not possible, asoften happens in the prior constructions of double valve of a hydraulicbrake, on a sudden increase in pressure (for .example by a rise intemperature) for the valve to'be lifted and, before it can close again,for such a large quantity of fluid to flow from the pressure cylinderand the brake conduits into the supply container that the positivepressure of the cylinder, in the released condition of the brakes, islost. The supply of pressure fluid in the spaces 9 and 35, according tothe invention, provides a compensation of volume variations in the fluidin the brake conduits and the brake cylinders in the vehicle wheels,which would otherwise occur with temperature changes. By means of thearrangement of a storage space or chamber 35 for the fluid between themain piston 2 and the auxiliary piston 28, the brake pedal or the handlever has, under all circumstances, an equally long stroke, as a resultof which the certainty of braking actionis considerably increased.

I claim: l 1

1. In a pressure device for hydraulic brakes of motor vehicles a masterpressure cylinder, a differential Working piston in the cylinder andforming therewith an annular chamber and a fullsurfaced chamber atopposite sides of the piston, pressure piping connected to the annularchamber of the cylinder, a pressure valve in a passage between saidchambers and opening-towards the annular chamber, means for connectingthe mannular chamber and the full-surface chamber of the'master cylinderin the rest position of the piston, an auxiliary piston disposed in acylinder chamber between the differential piston and a fluid supply, apressure spring loading the auxiliary piston towards the working piston,a stop for the two p-isto'nsbetween them and a spring loaded suctionvalve located in the auxiliary piston and opened by the suction strokeof the working piston.

2. In a pressure device for hydraulic'brakes of motor vehicles a masterpressure cylinder, a differential working piston in the cylinder andforming therewith an annular chamber and a full-surfaced chamber atopposite sides of the piston, pressure piping connected to the annularchamber of the cylinder, a pressure valve in a passage between saidchambers and opening towards the annular chamber, means for connectingthe annular chamber and the full-surface chamber'of the master cylinderin the rest position of the piston, an auxiliary piston disposed in themaster cylinder coaxially with the working piston between thedifferential piston and a fluid supply, a pressure spring loading theauxiliary piston towards the workingpiston, a stop for the two pistonsbetween them and a spring loaded suction valve located in the auxiliarypiston and opened by the suction stroke of the working piston.

I 3. In a pressure device for hydraulic brakes of motor vehicles amaster pressure cylinder, a differential working piston in the cylinderand. forming therewith an annular chamber and a full-surfaced chamber atopposite sides of the piston, pressure piping connected to the annularchamber of thelcylinder, a pressure valve in a passage between saidchambers and opening towards the annular chamber, means for connect ingthe annular chamber and the full-surface chamber of themaster cylinderinthe rest position of the piston, an auxiliary piston disposed in acylinder chamber between the differential piston and a fluid supply,apressure springloading the auxiliary piston towards the workingpisdifierential working piston in the cylinder and forming therewith anannular chamber and a full-surfaced chamber at opposite sides of thepiston, pressure iping connected to the annular .chamber of thecylinder, a pressure valve in a .passage between said chambers andOpening towards the annular chamber, means for connecting the annularchamber and the full-surface chamber of the master cylinder in the restposition of the piston, an auxiliary piston disposed in the mastercylinder coaxially with the work- .ing piston between thedifierentialpiston anda -fiuid supply, a pressure spring loading the auxiliarypiston towards the working piston, a stop for. the two pistonsbetweenthem, a spring loaded suction valve located in the auxiliary piston andopened by the suction stroke of the working piston, and a stop arrangedat the end of the master cylinder and lifting the suction valve in theauxiliary piston on the end of the backward stroke of the said piston.

5. In a pressure device for hydraulic brakes of motor vehicles a masterpressure cylinder, a differential working piston in the cylinder andforming therewith an annular chamber and a full-surfaced chamber atopposite sides of the piston, pressure piping connected to the annularchamber of the cylinder, a pressure valve in a passage between saidchambers and opening towards the annular chamber, means for connectingthe annular chamber and the full-surface chamber of the master cylinderin the rest position of the piston, an auxiliary piston disposed in acylinder chamber between the difierential piston and a fluid supply, apressure spring loading the auxiliary piston towards the working piston,a stop for the two pistons between them, a spring loaded suction valvelocated in the auxiliary piston and opened by the suction stroke of theworking piston, the packing cup of the auxiliary piston forming a seatof the said suction valve.

6. Ina pressure device for hydraulic brakes of motor vehicles a masterpressure cy1inder,'a differential working piston in the cylinder andforming therewith an annular chamber and a fullsurfaced chamber atopposite sides of the piston, pressure piping connected to the annularchamber of the cylinder, a pressure valve in a passage between saidchambers and opening towards the annular chamber, means for connect ingthe annular chamber and the full-surface chamber of the master cylinderin the rest position of the piston, an auxiliary piston disposed in themaster cylinder coaxially with the work- 'ingwpiston between thedifferential piston anda :fiuid supply, a pressure spring loading theauxiliary piston towards the working piston, a stop for the'two pistonsbetween them, a springloaded suction valve located in the auxiliarypiston and opened by the suction stroke of the working piston, thepacking cup of the auxiliary piston forming alseat or" the said suctionvalve.

1 7. In a pressure device for hydraulic brakes of motor vehicles amaster pressure cylinder, a differential working piston in the cylinderand forming-therewith an annular chamber and a full-,

surfaced chamber at opposite sides of the piston,.pressure pipingconnected to the annular chamber of the cylinder, a pressure valve in apassage between said chambers and opening towards :the annular chamber,means for connecting the annular chamber and the full-surface chamber ofthe master cylinder in the rest position of the piston, an auxiliarypiston disposed in a cylinder chamber between the difierential pistonand a fluid supply, a pressure spring loading the auxiliary pistontowards the working p-iston, a stop for the two pistons between them, aspring loaded suction Valve located in the aux-'- iliary piston andopened by the suction stroke or the Working piston, the packing cupofthe auxiliary piston forming a seat of the said suctionvalve, and a stoparranged at the end of the chamber of the auxiliary piston and liftingthe suction valve in the said piston on the end of the backward strokeof the auxiliary piston.

, 8. In a pressure device for hydraulic brakes'of motorlvehicles amaster pressure cylinder, a differential working piston in the cylinderand form'- ing therewith an annular chamber and a fullsurfaced chamberat opposite sides of the piston, pressure piping connected to theannular chamber of the cylinder, a pressure valve in a passage betweensaid chambers and opening towards the annular chamber, means forconmeeting the annular chamber and the full-surface chamber of themaster cylinder in the rest position of the piston, an auxiliary pistondisposed in the master cylinder coaxially with the working pistonbetween the differential piston and a. fluid supply, a pressure springloading the auxiliary piston towards the working piston, a stop for thetwo pistons between them, a spring loaded suction valve located in theauxiliary piston and opened by the suction stroke of the working piston,the packing cup of the auxiliary piston forming a seat of the saidsuction valve, and a stop arranged at the end of the chamber of theauxiliary piston and lifting the suction valve in the said piston on theend of the backward stroke of the auxiliary piston.

9. In a pressure device for hydraulic brakes of motor vehicles a masterpressure cylinder, a differential working piston in the cylinder andforming therewith an annular chamber and a fullsurface chamber atopposite sides of the piston, pressure piping connected to the annularchamber of the cylinder, a pressure valve in a passage between saidchambers and opening towards the annular chamber, means for connectingthe annular chamber and the full-surface chamber of the master cylinderin the rest position of the piston, an auxiliary piston disposed in acylinder chamber between the differential piston and a fluid supply, apressure spring loading the auxiliary piston towards the working piston,a stop for the two pistons between them, a spring loaded suction valvelocated in the auxiliary piston and opened by the suction stroke of 15,

the working piston, the packing cup of the auxiliary piston forming aseat of the said suction valve, and a stop arranged at the end of themaster cylinder and lifting the suction valve in the auxiliary piston onthe end of the backward stroke of the said piston.

10. In a pressure device for hydraulic brakes of motor vehicles a masterpressure cylinder, a differential working piston in the cylinder andforming therewith an annular chamber and a full-surfaced chamber atopposite sides of the piston, pressure piping connected to the annularchamber of the cylinder, a pressure valve in a passage between saidchambers and opening towards the annular chamber, means for connectingthe annular chamber and the full-surface chamber of the master cylinderin the rest position of the piston, an auxiliary piston disposed in themaster cylinder ccaxially with the working piston between thedifferential piston and a fluid supply, a pressure spring loading theauxiliary piston towards the working piston, a stop for the two pistonsbetween them, a spring loaded suction valve located in the auxiliarypiston and opened by the suction stroke of the working piston, thepacking cup of the auxiliary piston forming a seat of the said suctionvalve, and a stop arranged at the end of the master cylinder and liftingthe suction valve in the auxiliary piston on the end of the backwardstroke of the said piston.

11, In a pressure device for hydraulic brakes of motor vehicles, amaster pressure cylinder, a differential working piston in the cylinderand forming therewith an annular chamber and a fulland a spring loadedsuction valve located in the auxiliary piston and opened by the suctionstroke of the working piston. I

12. In a pressure device for hydraulic brakes of motor vehicles, amaster pressure cylinden a differential working piston in the cylinderand forming therewith an annular chamber and a full-surfaced chamber atopposite sides of thepiston, pressure piping connected to the annularchamber of the cylinder, a pressure valve in a passage in the workingpiston between said chambers and opening towards the annular chamber, astop lifting the said pressure valve off 1 its seatin the rest positionof the working piston, an auxiliary piston disposed in a cylinderchamber between the differential piston and a fluid supply, a pressurespring loading the auxiliary piston towards the working piston, a stopfor the two pistons between them and a spring loaded suction valvelocated in the auxiliary piston and opened by the suction stroke of theworking pis ton.

JIRi BELEN'KIJ.

